Such stabilizers are used especially in automotive engineering.
One stabilizer, which operates according to the principle of a torsion bar and is directed in parallel to the vehicle axle, is associated, in principle, with each axle of a motor vehicle. The two ends of the stabilizer are fastened to the respective wheel suspension. This stabilizer prevents or substantially weakens the transmission of the rolling movements originating from the road conditions to the vehicle.
There are one-part stabilizers, which are designed for a predetermined spring rate only and therefore respond either too softly or too harshly to varying loads. They are therefore unsuitable for vehicles that are designed for both the road and terrain.
Vehicles that are subject to such loads are usually equipped with a split stabilizer. Such a split stabilizer is known, for example, from DE 100 12 915 A1, in which the two stabilizer parts are connected by an actuator in the form of a switchable coupling. This actuator comprises an outer rotary part, which is connected via a cover with one stabilizer part, rotating in unison therewith, and an inner rotary part, which is connected directly with the other stabilizer part, rotating in unison therewith. Both the inner rotary part with one stabilizer part and the cover of the outer rotary part with the other stabilizer part are made of one piece each.
This design solution leads to individual parts that are complicated in terms of manufacturing technology because the stabilizer part has a curved shape and a great length. The manufacturing technological difficulties are further increased, especially in the case of the stabilizer part with the cover, by the fact that the end of the complicated stabilizer part must be processed by forming to manufacture the cover.
DE 42 29 025 A1 describes a split stabilizer, whose stabilizer part with the cover of the outer rotary part is welded by a laser beam. Such a welded connection does not meet the requirements imposed on the strength for the transmission of the high and varying torques because the stabilizer part consists of spring steel and the cover of a case-hardened material and, in particular, spring steel is not considered to be weldable. The high welding temperatures lead to cracking during the phase of cooling.
In addition, laser beam welding is ruled out for cost reasons because a special laser welding machine with complicated devices becomes necessary for it.
A split stabilizer with an actuator, in which the cover of the outer rotary part has internal teeth and the corresponding stabilizer part has external teeth, is known from U.S. Pat. No. 5,700,027. Such teeth are, however, usually subject to a clearance due to the manufacturing technology, which is functionally manifested as a slip between the two rotary parts. To avoid this drawback, it is generally known to attach the cover with its internal teeth on the external teeth of the stabilizer part by kneading. Even though the clearance is thus eliminated, the load-bearing capacity of these teeth decreases in turn.
Such teeth are also not secured axially, so that a radial pin must be additionally inserted, and this pin further reduces the material thickness of the torque-transmitting parts, on the one hand, and is difficult to machine because of the high quality of the material, on the other hand, and it needlessly increases the manufacturing costs. Another drawback is that the teeth do not guarantee sealing toward the outside. Additional sealing elements, which seal the interior of the working chambers of the actuator toward the outside, are therefore necessary. This also makes the stabilizer more expensive.